1. Field of the Invention
The present invention generally relates to a fluid temperature control apparatus, particularly to a fluid temperature control apparatus suitable for performing precise control of the temperature of corrosive fluid used as processing solution in semiconductor manufacturing apparatus or the like.
2. Description of a Related Art
In the processing of semiconductor such as etching, cleaning, resist peeling or the like, generally, highly pure and highly corrosive chemical fluids are used. Reaction speed of these chemical fluids highly depends on the temperature thereof. In order to precisely control the reaction of a chemical liquid, it is necessary to control the temperature of the chemical fluid with high accuracy within, for example, a range from 15xc2x0 C. to 85xc2x0 C. Various temperature control apparatus are used for such temperature control.
FIG. 8 is a schematic plan view showing a structure of a conventional fluid temperature control apparatus.
The fluid temperature control apparatus 100 has a heat transfer chamber 101 formed in a block made of a corrosion resistant material such as fluorocarbon series resin or the like. Heat is transferred from a temperature control apparatus such as a thermoelectric element module or the like to the fluid passing through within the heat transfer chamber 101. The inside of the heat transfer chamber 101 is divided into four partitions 105 in the depth direction by three flow path forming plates 103. In one end of each flow path forming plate 103, opening 107 is formed. The openings 107 are disposed alternately in the ends of the three flow path forming plates 103. Owing to such constitution, the respective partitions 105 are linked to each other via the openings 107 to form a flow path which meanders within the heat transfer chamber.
To the two partitions 105 at the top and bottom in the heat transfer chamber 101, pipes are connected which are linked to these partitions 105, respectively. One of the pipes is a fluid intake pipe 109 and the other thereof is a fluid outlet pipe 111. The respective pipes are connected to the respective partitions at the position far from the openings 107 of the flow path forming plate 103. The fluid, which enters into the heat transfer chamber 101 from the fluid intake pipe 109, is subjected to heat release or heat absorption by the temperature control apparatus while meandering within the heat transfer chamber, and the temperature thereof is controlled. Then, the temperature-controlled fluid is supplied to the next process through the fluid outlet pipe 111. Detailed information about the fluid temperature control apparatus as shown in FIG. 8 is disclosed in Japanese patent application publication JP-A-11-67717.
FIGS. 9A and 9B are schematic views of a structure of another conventional fluid temperature control apparatus. FIG. 9A is a side view thereof, and FIG. 9B is a sectional view taken along a line IVxe2x80x94IV in FIG. 9A. The fluid temperature control apparatus 120 has a heat transfer chamber 121 as shown in FIG. 9A. On the top and bottom surfaces of the heat transfer chamber 121, heat transfer plates 123 are attached respectively. The heat transfer plates 123 is connected with a temperature control apparatus such as thermoelectric element module and performs heat release or heat absorption on the heat transfer chamber 121 under the control of the temperature control apparatus. Further, the heat transfer chamber 121 has an upper partition 125 and a lower partition 127 of the heat transfer chamber with holes 129a and 129b that links both partitions to each other. As shown in FIG. 9B, each of the upper partition 125 and the lower partition 127 is divided into two portions by a partitioning wall 131. To the side surfaces of the heat transfer chamber 121 where the holes 129a and 129b are formed, a fluid intake pipe 133 and a fluid outlet pipe 135 are connected, respectively.
The fluid entered into the hole 129a via the fluid intake pipe 133 is divided in the partitions and branched into the upper partition 125 and the lower partition 127, and flows so as to make a U-turn along the partitioning wall 131 in the respective partitions. During this, the temperature thereof is controlled by the thermoelectric element module or the like. And then, the fluids congregate at the hole 129b to flow out from the fluid outlet pipe 135 to the next process.
In the fluid temperature control apparatus as described above, in order to precisely control the temperature of the fluid, it is necessary that the fluid comes into contact with the thermoelectric element evenly while flowing in the flow path. Accordingly, it is necessary to form the flow path so as to reduce as few as possible such portions where the flow of the fluid becomes irregular, for example, where swirl of the fluid is generated in the heat transfer chamber or where the speed of flow gets slow to cause a stagnation. Further, when chemical fluid is removed from the apparatus after operation, in order to prevent the chemical fluid to be used next time from being contaminated thereby, it is necessary to completely empty the apparatus so as to leave no chemical fluid therein. Furthermore, it is preferred to adapt the depth in the heat transfer chamber to be very shallow so that the fluid is subjected effectively to the heat transfer.
However, in the conventional example as shown in FIG. 8, since the capacity of the heat transfer chamber 101 is large and the heat transfer chamber 101 is deep, there is a possibility that the performance to transfer the heat to the entire fluid becomes not even. Further, the flow path forming plates 103 are attached to the side surface of the heat transfer chamber 101 and inserted into the grooves formed therein. Due to this, a gap may be generated between the groove and the plate 103 allowing the chemical fluid to enter therein. Thus, a solid may crystallize out there from the chemical fluid. Still further, since the flow path has a meandering configuration as described above, the chemical fluid is apt to be left at the corners of the respective partitions 105 when the chemical fluid is drained.
Still furthermore, in the conventional embodiment as shown in FIGS. 9A and 9B, in the flow path constituted of the upper partition 125 and the lower partition 127, the flow speed of the fluid near the partitioning wall 131 is different from that at the outer side thereof, and the fluid may stagnate at the corners of the respective flow paths.
Accordingly, it is necessary to form the flow path so as not to form a cornered portion or extremely narrow portion. Further, in the case where the flow path has a certain depth, the effect of the temperature controlling member may not reach to the central region of the fluid failing in even temperature control. Accordingly, a fluid temperature control apparatus is required in which the layer of the fluid is made to be as thin as possible to increase the amount of the fluid that comes into contact with the temperature controlling member and which is provided with a flow path generating no swirl nor stagnation. Furthermore, it is more preferred if the chemical fluid can be removed completely.
On the other hand, another problem remains as described below in the conventional fluid temperature control apparatus. Generally, the heat transfer chamber is made by carving a block-like material (heat transfer block) to form concave portions and covering the concave portions with high heat conductive plates. To the plates, thermoelectric element modules for performing the temperature control come into contact therewith, and via the plates, heat exchange is performed between the fluid in the heat transfer chambers and the thermoelectric element modules. The contact points between the heat transfer block and the high heat-conductive plates are made to come into tight contact with each other by means of a sealing member such as an O-ring, and thereby the fluid is prevented from leaking from the heat transfer chamber formed by the both.
The heat transfer block is made of a material such as fluorocarbon series resin which is excellent in corrosion resistance. Generally, such material as described above has a large coefficient of linear expansion (for example, approximately ten times as large as that of iron), and is apt to suffer plastic deformation. Accordingly, such problem remains that, when heating and cooling of the heat transfer block are repeated, a dimensional reduction is caused in the pressure welding direction, contact pressure at the sealing portions between the heat transfer block and the high heat-conductive plates lowers resulting in a gap, and therefore, the fluid in the heat transfer chamber leaks therefrom.
In order to solve the problems as described above, FIG. 5 of JP-A-11-67717 shows that the heat transfer block and the heat exchanger plates are fixed by using bolts and conical springs. That is to say, by selecting the number of conical springs or overlapping direction thereof, compression force of the entire conical springs is increased, or the extension and compaction of the conical springs are increased to largely absorb the dimensional reduction due to the plastic deformation.
However, in these days, the temperature controllable range required for the fluid temperature control apparatus has been getting larger and larger. Since the amount of plastic deformation of the heat transfer block is getting larger, there may be a case where the mechanism as describe above cannot absorb the amount of deformation sufficiently, or a case where the durability of the apparatus itself is affected by repeating such deformation as described above.
The present invention has been achieved in view of the above-described problems. A first object of the present invention is to provide a fluid temperature control apparatus capable of performing precise control of the temperature, in which a high sealing performance in a heat transfer chamber is maintained even under a situation of repetitive thermal cycle accompanying the cooling and heating. Further, a second object of the present invention is to provide a fluid temperature control apparatus in which the chemical fluid hardly remains in the heat transfer chamber when the chemical fluid is drained therefrom.
In order to solve the above-described problems, a fluid temperature control apparatus according to the present invention comprises a block member formed with at least one inflow port and at least one outflow port for fluid, and concave portion which constitutes a part of a heat transfer chamber for controlling temperature of the fluid by allowing the fluid to pass therethrough; a heat transfer plate which constitutes the heat transfer chamber by covering the concave portion of the block member; holding means for holding the block member and the heat transfer plate such that the contact portions thereof come into tight contact with each other, the holding means holding the block member and the heat transfer plate by using an elastic member so as to prevent plastic deformation of the block member by means of expansion and contraction of the elastic member following thermal expansion and thermal contraction of the block member respectively; and temperature controlling means for performing heat exchange with the fluid, which passes through the heat transfer chamber, via the heat transfer plate.
According to the present invention, the block member and the heat transfer plate are held being compressed by using holding means including an elastic member. Therefore, even when a thermal deformation is generated in the block member, an amount of the thermal deformation is absorbed by the elastic member, thereby plastic deformation is prevented from being generated on the block member while maintaining the sealing performance between the block member and the heat transfer plates.